In certain large scale facilities for production, treatment, storage and distribution of gas and liquid products there are a large number of conventional air cooled heat exchangers. These facilities sometimes experience substantially excessive high power consumption and low performance due to fouling accumulation on external surfaces of cooling fins as heat exchange tubes. This is particularly true in an environment like that of Saudi Arabia where the air is filled with heavy dust so that tube bundles of air cooled heat exchangers become externally plugged in a short period of time and require frequent and extensive cleaning. Existing cleaning methods are known to be both expensive and not fully successful because of heat exchanger construction where many tubes with their closely spaced fins are packed in relatively tight bundles. Many surfaces are not reached by the cleaning liquid or spray since many are below or otherwise blocked by others closer to the source of the cleaning spray. The same problem exists even with mechanical brushing or scraping, as there are such a great many areas that are simply not accessible.
In applicant's various facilities there are together more than 15,000 air cooled heat exchangers that are regularly fouled and require frequent and repeated cleaning. The estimated cleaning cost by a company-wide survey was $12 million annually, without even considering other costs from slowdown or (operation bottlenecking) or other process interruptions. The above-noted cost does not include other mechanical damage caused by conventional types of cleaning to the fins and heat exchange tubes.
The present invention seeks to provide a new and improved apparatus and method for cleaning the external surfaces of finned tubes of air cooled heat exchangers.